Count formula

[lionelnz]

Good evening all.

I wish to generate a simple invoice based on the YYMM number of occurrences for a simple database to do a simple mailmerge.

Example the date of first invoice is 02/04/15 (dd/mm/yy format). I can easily generate the invoice 150401 with formula =text(date,"yymm")&"01") which gives 150401 but I want to generate the "01" automatically with some type of Countif(Range,Text("YYMM") so that it counts the number of times an invoice is generated for the month.

eg if I have a 2nd invoice dated 04/04/15 the formula will generate 150402 and all subsequent invoices will automatically count the number of dates in the month.

TIA in advance

 

[Aladin Akyurek]

A1: 02/04/15

A2, copied down:

=TEXT(A1,"yymm")&TEXT(ROWS($A$2:A2),"00")

 

[lionelnz]

This what I have researched and altered for me -

=TEXT(I5,"YYMM")&TEXT(SUMPRODUCT(--(TEXT($I$2:I5,"mmyyyy")=TEXT(I5,"mmyyyy"))),"00")

and to be safe I enter it as an array formula.